Dominguez Johana Elizabeth, Rosario Lovera, Juliana Sánchez, Redondo Leandro Martin, Chacana Pablo Anibal, Regino Cavia, Fernández Miyakawa Mariano Enrique
Laboratorio de Bacteriologia General, Instituto de Patobiología Veterinaria, Instituto Nacional de Tecnología Agropecuaria-Consejo Nacional de Investigaciones Científicas y Tecnológicas (IPVet), INTA-CONICET, William C. Morris, Argentina.
Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), UBA-CONICET, Ciudad Autónoma de Buenos Aires, Argentina.
Zoonoses Public Health. 2023 Nov;70(7):627-635. doi: 10.1111/zph.13071. Epub 2023 Jul 4.
Rattus norvegicus and Rattus rattus are commensal pest rodents, considered reservoirs and vectors of zoonotic pathogens. In livestock farms, the wide use of antimicrobials and their release into the environment lead to high long-term residual concentrations, which may in turn lead to the occurrence of antimicrobial resistance (AMR). Farm environments serve as AMR sources, resulting in the transmission of antimicrobial-resistant bacteria and their AMR genes of livestock origin into wildlife. This study aimed to analyse the profile of enterobacteria carrying AMR determinants in rats captured in livestock farms to determine their potential vectors as for the spread of AMR. To this end, 56 rats (52 R. norvegicus and 4 R. rattus) were live-trapped on 11 farms (pig, dairy, poultry and mixed farms) located in central Argentina, from spring 2016 to autumn 2017. From 50 of the R. norvegicus individuals and three of the R. rattus individuals found in 10 of the farms, we isolated 53 Escherichia coli and five Salmonella strains. Susceptibility to antimicrobials, genotypic profiles, minimal inhibitory concentration of colistin and the presence of mcr-1 and genes encoding extended-spectrum β-lactamase (ESBL) were determined. Of the 58 isolates not susceptible to different antimicrobial classes, 28 of the E. coli strains and two of the Salmonella strains were defined as multi-drug resistant (MDR). S. Westhampton and S. Newport recovered were not susceptible to ampicillin or all the cephems tested. One of the E. coli obtained showed resistance to colistin and harboured the mcr-1 gene, demonstrated by PCR and conjugation. In two ESBL-producing Salmonella isolated from rats, CTX-M-2 genes were responsible for the observed resistance to third-generation cephalosporins. The MDR E. coli isolates showed several different resistance patterns (23), although some of them were the same in different individuals and different farms, with six resistance patterns, evidencing the dispersion of strains. These findings suggest that rats play a role in the dissemination of AMR determinants between animal, humans and environmental reservoirs.
褐家鼠和黑家鼠是共生害鼠，被认为是人畜共患病原体的宿主和传播媒介。在畜牧场，抗菌药物的广泛使用及其向环境中的释放导致长期残留浓度较高，这反过来可能导致抗菌药物耐药性（AMR）的出现。农场环境是AMR的来源，导致源自家畜的抗菌药物耐药细菌及其AMR基因传播到野生动物中。本研究旨在分析在畜牧场捕获的大鼠中携带AMR决定因素的肠杆菌谱，以确定它们作为AMR传播潜在媒介的可能性。为此，2照16年春季至2017年秋季期间，在阿根廷中部的11个农场（养猪场、奶牛场、家禽场和混合农场）活捉了56只大鼠（52只褐家鼠和4只黑家鼠）。在10个农场中发现的50只褐家鼠个体和3只黑家鼠个体中，我们分离出了53株大肠杆菌和5株沙门氏菌菌株。测定了它们对抗菌药物的敏感性、基因型谱、黏菌素的最低抑菌浓度以及mcr-1和编码超广谱β-内酰胺酶（ESBL）基因的存在情况。在58株对不同抗菌药物类别不敏感的分离株中，28株大肠杆菌菌株和2株沙门氏菌菌株被定义为多重耐药（MDR）。回收的韦斯特汉普顿沙门氏菌和纽波特沙门氏菌对氨苄西林或所有测试的头孢菌素均不敏感。获得的一株大肠杆菌对黏菌素耐药并携带mcr-1基因，经PCR和接合试验证实。在从大鼠分离出的两株产ESBL的沙门氏菌中，CTX-M-2基因导致观察到对第三代头孢菌素的耐药性。MDR大肠杆菌分离株表现出几种不同的耐药模式（23种），尽管其中一些在不同个体和不同农场中是相同的，有6种耐药模式，证明了菌株的传播。这些发现表明，大鼠在动物、人类和环境宿主之间AMR决定因素的传播中起作用。
